The International Atomic Energy Agency (IAEA) was established in 1957 as part of the United Nations to “promote safe, secure and peaceful use of nuclear technology” among member nations. World concern was growing in the early 1950s over the discovery of nuclear energy which could be used as a peaceful source of energy or as a terrible weapon. U.S. President Dwight Eisenhower gave his famous “Atoms for Peace” address at the UN in 1953 which inspired the creation of the IAEA.

            According to the mission statement, the “IAEA is :

• is an independent intergovernmental, science and technology-based organization, in the United Nations family, that serves as the global focal point for nuclear cooperation;
• assists its Member States, in the context of social and economic goals, in planning for and using nuclear science and technology for various peaceful purposes, including the generation of electricity, and facilitates the transfer of such technology and knowledge in a sustainable manner to developing Member States;
• develops nuclear safety standards and, based on these standards, promotes the achievement and maintenance of high levels of safety in applications of nuclear energy, as well as the protection of human health and the environment against ionizing radiation;
• verifies through its inspection system that States comply with their commitments, under the Non-Proliferation Treaty and other non-proliferation agreements, to use nuclear material and facilities only for peaceful purposes.”

            The IAEA is the primary intergovernmental nuclear power agency in the world. It has a board of governors and representatives from member states. Conferences are held to determine policies for the organization. The IAEA is composed of the several departments to deal with different aspects of nuclear energy.

            The Department of Nuclear Energy is involved with nuclear power engineering, nuclear power technology development, nuclear power infrastructure, nuclear fuel cycles and waste technology, research reactors, nuclear power planning and economic studies, international nuclear information systems and nuclear knowledge management.

            The Nuclear Safety and Security department is concerned with a nuclear safety and security framework, safety and security technical issues, services for member states, publications, standards and guidelines, conventions and codes, conferences, and training and special projects.

            The Nuclear Sciences and Applications department deals with nuclear issues involving  food and agriculture, human health, cancer therapies, the environment, water resources, radioisotope production and radiation technology and nuclear science in general.

            The Safeguards department was established to provide a nuclear safeguards legal framework including legal treaties and agreements, resources for states, publications including texts of safeguard agreements and protocols, status updates on agreements and protocols, analysis tools, and a forum for discussion of related topics.

            The Technical Cooperation department covers nuclear technical cooperation history, policy context, relationships with the United Nations, programs, frameworks for cooperation, regional breakdown of cooperation, publications and online tools for the technical cooperation community.

            In addition to these departments, the IAEA also provides a new center with top stories and features related to nuclear issues, press releases, multimedia presentations and the IAEA bulletin. An archive of documents includes annual reports, information circulars, treaties and conventions, standards and guidelines, legal agreements and protocols for safeguards.

            After the Fukushima nuclear accident, the IAEA’s response was criticized as being “sluggish and confusing.” Nuclear experts state that the IAEA has a complicated mandate and is constrained by its member states who do not have to follow IAEA safety standards. These problems will make reforms difficult. Calls have been made to change the mandate of the IAEA to make so it can do a better job of policing nuclear power plants across the globe.

 

            In 1974 the Energy Reorganization Act broke up the Atomic Energy Commission and established the Energy Research and Development Administration to promote civilian nuclear power and to oversee civilian nuclear research, nuclear weapons development and naval reactor program. The ERDA was combined with the Federal Energy Administration in 1977 to create the U.S. Department of Energy (DOE). The DOE has a number of departments that deal with nuclear materials, research and weapons development.

            The Office of Civilian Radioactive Waste Management (OCRWM) was established in 1982 to be responsible for the disposal of radioactive waste in the United States. From the World War Manhattan Project to the end of the Cold War in 1991, huge amounts of nuclear waste were generated as civilian nuclear power spread and a massive nuclear weapons stockpile was created in the US. With the creation of the DOE in 1977, the OCRWM was created to deal with the problem of permanent disposal. Since the early 1980, the OCRWM has dedicated most of its efforts to the creation of a nuclear waste depository at Yucca Mountain in southern Nevada. By 2005, over fifty thousand metric tons of spent nuclear fuel from civilian reactors had accumulated. Military nuclear waste was estimated to eventually comprise over twenty thousand canisters of solid waste. In 2005 it was discovered that some of the research on possible water infiltration of the Yucca Mountain Repository had be falsified in the 1990s to minimize concerns. The OCRWM is also responsible for the transport of nuclear waste from existing sites to the Repository.

            The Office of Legacy Management was created in 2003 to deal with radioactive and chemical contamination at over 100 sites across the U.S. Many of these sites were once used to develop, build and test nuclear weapons but have been shut down. The contamination exists in water, soil, landfills and in the buildings of the closed facilities. Because of the long half lives of radioactive isotopes used in nuclear weapons, the OLM will have to secure and decontaminate those sites for generations.

            The Office of Nuclear Energy was established to “promote nuclear power as a resource capable of meeting the Nation’s energy, environmental and national security needs by resolving technical and regulatory barriers through research, development and demonstration.” Some of its programs include working to improve reactor design and performance, managing research facilities, working on waste and proliferation issues, insuring adequate supplies of fuel for world nuclear reactors, trying to extend the lifespan of existing reactors and working on nuclear batteries for space and national security applications.

            The National Nuclear Security Administration (NNSA) was created in 2000 to manage and secure U.S. nuclear weapons, work against nuclear proliferation and develop naval nuclear reactors. It was also tasked with responding to nuclear and radiological emergencies in the U.S. The NNSA provides safe and secure transportation for nuclear weapons, nuclear weapon components and special nuclear materials.

 

 

In 1974 the Energy Reorganization Act broke up the Atomic Energy Commission and established the Nuclear Regulatory Commission (NRC) to assume duties for regulating the U.S. nuclear industry. These duties include radioactive materials safety, reactor licensing and renewal, reactor safety and reactor security. They also include monitoring and regulation of the storage, security, recycling and disposal of spent nuclear fuel.

            The NRC is divided into four regions of the United States. Region I covers the northeastern states, Region II covers the southeastern states, Region III covers the Midwestern states and Region IV covers the western and south central states. There are 104 reactors producing electrical power and 36 reactors used for other purposes in these regions. Each of the reactors that produce power have onsite NRC inspectors to monitor daily operations. NRC Teams composed of a variety of specialists periodically carry out targeted inspections at the reactors. There are provisions for whistleblowers to report problems as part of the special NRC Allegations Program. Unfortunately there are cases where a whistleblower pointed out illegal practices which it turned out that the NRC had been aware of and had failed to respond to. The NRC also monitors training programs for nuclear workers and accreditation of training facilities.

            Like the Atomic Energy Commission before it, there has been concern that the NRC is not doing a competent job of regulating the nuclear industry and has become a servant instead, a situation called regulatory capture. The NRC has been found to have failed to enforce its regulations thoroughly and uniformly on the 104 nuclear power reactors and their operators. This failure to enforce regulations was found to not only be a matter of incompetence and neglect but the NRC has actually stated that it chooses not to enforce regulations in some cases. The NRC has been accused of surrendering some of its regulatory authority to the Institute for Nuclear Power Operations which was formed by the nuclear industry. In addition, at times the NRC has apparently made it difficult for the public to obtain information about and to participate in regulation of the nuclear industry. In spite of the Three Mile Island accident in 1979, the NRCs record of regulatory effectiveness has continued to decline.

            Many nuclear power plants have reached or are approaching the end of their projected fourty year life span. Operators have applied for and been granted twenty year extensions of their licenses by the NRC even though state legislatures and objected and a pattern of lies by plant operators with respect to dangerous safety issues has been ignored by the NRC. The Union of Concerned Scientists issued a report in 2011 stating that the NRC enforcement of safety rules has not been “timely, consistent, or effective.” The report claims that serious accidents have been narrowly avoided on a number of occasions because of NRC negligence.

            Following the Fukushima disaster in March of 2011, a group of concerned organizations and individuals have formally petitioned the NRC to “immediately suspend all licensing and other activities at 21 proposed nuclear reactor projects in 15 states until there is a thorough examination of all existing and proposed reactors. In response to pressure, the NRC is moving forward to implement new safety procedures to enable nuclear plant operators to adequately cope with natural disasters such as earthquakes and tsunamis. We can only hope that the NRC become more effective before a major disaster destroys reactors and shuts down part of the power grid in the United States.

 

 

 

In 1946 President Harry S. Truman transferred control of atomic energy development from the military to civilian control by signing the McHahon/Atomic Energy Act. This Act created the Atomic Energy Commission or AEC. Congress passed the act after extensive debate involving scientist, military men and politicians over the future of atomic energy. The mandate of the commission was to “promote world peace, improve public welfare and strengthen free competition in private enterprise.”

            The Act which created the AEC gave it power to regulate the entire field of nuclear science and technology. Transfer of nuclear technology between the United States and other countries was prohibited and the FBI was charged with policing access to nuclear information. The AEC was granted a great deal of power and independence with its employees being exempt from the Civil Service rules. All production facilities and nuclear reactors would be owned by the federal government while laboratories such as Argonne National Laboratory would be under the control of the AEC.

            Although the AEC was charged with the development of peaceful uses of nuclear energy, most of its early work was dedicated to the development of the nuclear arsenal of the United States. The World War II Manhattan Project turned over its work to the new AEC which continued the evolution of atomic bomb as well as the development of the hydrogen bomb. The AEC oversaw two nuclear laboratories for weapons work, Los Alamos Scientific Laboratory and Lawrence Livermore National Laboratory. A project of nuclear testing was implemented in the American Southwest and an area in the Pacific Ocean.

            The General Advisory Committee of the AEC provided technical and scientific advice. A Military Liaison Committed was a bridge between the AEC and the United States Military. The Congressional Joint Committee on Atomic Energy provided oversight. With its great power over all things nuclear in the United States, the AEC was the center of controversies.

            The AEC was in charge of all regulation of nuclear facilities. The Atomic Energy Act Amendments of 1954 cleared the way for the development of civilian nuclear reactors to provided electricity. This act required the AEC to both promote civilian nuclear power and to insure its safety. These contradictory mandates would prove to be difficult to reconcile.

            During the 1960s, critics claimed that the AEC regulations were not strong enough with regard to radiation protection, nuclear reactor safety, siting of power plants, danger to the environment and other concerns.

            In the early 1970s, the construction of nuclear power plants declined due to increasing construction costs and lowering demand for electricity. Construction of some partially built plants was halted. In 1974, Congress responded to criticisms of the AEC by abolishing the agency. The Energy Reorganization Act of 1974 created two new agencies. The Energy Research and Development Administration (ERDA) was set up to promote civilian nuclear power and to oversee civilian nuclear research, nuclear weapons development and naval reactor program. The ERDA was combined with the Federal Energy Administration in 1977 to create the U.S. Department of Energy. The Nuclear Regulatory Commission was also established by the 1974 Act to regulate the nuclear industry.

            With the enormous cost of nuclear power development, it was inevitable that there would be conflicts of interest in the AEC and absolutely necessary that its job be split between new agencies.

 

 

 

 

 

 

            There are a variety of types of nuclear accidents. This is a list of some of the main types.

            Nuclear reactors are basically furnaces that using radioactive materials to generate heat to drive steam turbines. They require large amounts of cooling water to operate properly. Depending on the type of reactor, the coolant that carries heat away from the reactor core may be converted directly to steam or it may transfer heat through a heat exchanger to turn water to steam in a separate system. Then there is another separate system that cools the steam back to water. A coolant accident can cause serious problems for a nuclear reactor. If coolant is lost in the reactor core, there is danger of exposure of fuel rods and meltdown. Loss of coolant in the steam system can result in releaser of radioactive isotopes in escaping steam. And, finally, if there is insufficient water to cool the steam, then the reactor cannot function.

            Nuclear reactors generate heat via a fission reaction. In order to maintain a steady output of energy, the fuel in the reactor core must achieve criticality or a self-sustaining fission reaction. The reaction must be controlled in order to prevent a runaway production of excess energy. Sometimes unintended criticality occurs in a fissile material in a reactor, a laboratory or a processing plant and this is called a criticality accident. This results in the expected and dangerous release of radioactivity.

            When accidents cause damage to and/or exposure of the reactor core, the resulting excess heat from radioactive decay is called a decay heat accident. The heat can cause exposure and melting of the fuel elements, damage to the reactor machinery, generation of steam which can breach the containment vessel or generation of hydrogen which can explode and  blow out the walls of the containment shell and the reactor building.

            Radioactive fuels and research materials must be transported which can result in nuclear transportation accidents. Trucks can be in wrecks, ships can founder, railcars can jump tracks and planes can crash. These can be unintentional accidents or can be deliberately caused. If these vehicles are transporting nuclear materials, a release of radioactive isotopes into the environment can result threatening water supplies, animals, plants and civilian populations.

            The design of nuclear reactors is still evolving. Either through poor design or accidents, equipment accidents can occur in nuclear power plants. Control systems can fail to moderate reactions in the core, sensors can fail to information operators of dangerous situation, valves can stick preventing coolant flow and automatic safety equipment can fail in critical situation. Software problems in control systems can also cause equipment accidents.

             

            As with any system operated by human beings there can be human errors in dealing with nuclear reactors and radioactive materials. Operators can fail to perceived problems through lack of training or inattention. Operators can do the wrong things at critical times for the same reasons. Workers can fail to report problems or can actually work to conceal them. Management can falsify records in order to conceal problems, save money or avoid adverse publicity.

            Radioactive materials can be lost, stolen or abandoned to become what is called an orphan source. If people who come across the orphan source do not realize that it contains radioactive material, they can be endangered by exposure.

            Deliberate illegal trafficking in nuclear materials is not exactly an accident in the sense of the rest of these items but is included in the list because of its unpredictability and danger. There is a black market in nuclear materials where terrorists attempt to purchase radioactive materials in order to build a nuclear bomb or create a dirty bomb to scatter radioactive material over a large area.

            A strong international effort to monitor the possession of, use, transport, handling and storage of nuclear materials is absolutely essential to the well being of the human race in the future.

            The Tokyo Electric Power Company (TEPCO) is a Japanese electric utility that serves an area around Tokyo Japan. It is one of ten regional electric utilities created in 1951. The company worked on rebuilding the Japanese infrastructure destroyed in World War II and expanding energy supply to Japan’s  developing industries. Responding to concerns about environmental pollution and rapidly rising oil prices in the 1960s and 1970s, TEPCO built nuclear power stations. In 1976, the Fukushima Number One power plant started generating electrical energy.

            During construction of the plant, TEPCO changed the design of the pipes for the isolation condensers without notifying the Japanese regulatory agencies as required by law. This may have contributed to the problems that followed the earthquake and tsunami in March of 2011.

            In 1976, TEPCO was warned of design problems with the plant design by one of the lead designers from GE. There were unreported problems at the plant that may have been related to these design flaws. When TEPCO was found to have falsified safety inspection records for vital cooling system components, they were forced to temporarily shut down all of the 17 nuclear reactors that they operated.

            In 1991, leaking seawater disabled one of two emergency backup generators at the Fukushima Unit 1 reactor. An engineer at Fukushima later said that he told his superiors that a tsunami could flood the generator room. TEPCO did not move the generators to a higher location but they did install a door to prevent flooding. In spite of this, the tsunami on March 11, 2011 did flood the generators room.

            In 2006,  a court order was issued to close a nuclear power plant in western Japan because of fears that an earthquake could damage the plant and release radioactivity. The Japanese Nuclear Safety Commission objected saying that the plant was adequately protected and was safe. The Japanese government opposed the court order.

            In 2008, there was an internal study by TEPCO on plant safety that raised concerns about tsunami caused flooding at Fukushima and recommended immediate steps to prevent such flooding. TEPCO management concluded that no such action was needed because the predicted flood level was not realistic. It was later found that TEPCO had conducted tsunami simulations that indicated that the estimated flood levels were very realistic and could occur. There were plans made to address the problem in 2011.

            In 2008, the International Atomic Energy Agency said that Japan’s nuclear reactors were at risk from major earthquakes.

            On March 7 of 2011, a report from TEPCO on the 2008 studies was delivered to the Nuclear and Industrial Safety Agency of MITI, the Japanese Trade ministry. Three days later,. the forecast disaster struck the Fukushima power station.

            Following the nuclear accident at Fukushima, investigations uncovered this decades long series of illegal, unethical and incompetent actions and inactions by TEPCO. The Japanese government has nationalized the Fukushima facility due to justified concerns about TEPCO’s ability to deal with the aftermath of the accident.

            Many years ago in a conversation about nuclear power, I said that while engineers might be able to design a safe nuclear power plant, we would have to rely on government and industry to be much more competent and honest than they had been in the past. The situation at Fukushima is a horrible validation of my concerns.

 

            The International Nuclear Event Scale (INES) is currently used to rank the severity of nuclear accidents. Since the Fukushima nuclear disaster in March of 2011, deficiencies of the INES have become more apparent. The INES is a subjective qualitative assessment of the seriousness of a nuclear accident. It functions more as a public relations tool than as n objective scientific scale. And, it confuses the magnitude of a nuclear event with the intensity.

            David Smythe is Emeritus Professor of Geophysics at the University of Glasgow, Scotland. He has been active in assessing the geology and hydrology of proposed nuclear waste repositories in the United Kingdom. In an article published in December of 2011, Symthe proposed a new scale to replace the INES. He calls the new scale nuclear accident magnitude scales (NAMS).

            The proposed new scale uses the earthquake magnitude approach where levels are defined in logarithmic jumps. In the earthquake Richter Scale, each level is ten times the magnitude of the level below it. In the NAMS, the magnitude of an event is equal to log(20R) where R is the off-site release of radioactivity calibrated in terms of equivalence to trillions of becquerels (TBq) of iodine-131.

            Where the levels of INES are simple integers, the magnitudes of the NAMS are actual numbers corresponding to the radiation release. The constant 20 in the NAMS equation is meant to synchronize the NAMS with the INES. The upper levels of the ranges of the NAMS are equal to the levels of the INES. For instance, 500 TBq is equal to the upper limit of level 4 in the INES scale and also equal to a NAMS magnitude 4.

            Where the INES scale only considers atmospheric contamination in levels 4 to 7, the NAMS scale is intended to only measure off-site atmospheric contamination. Water contamination is not considered in the NAMS scale although evaporation of contaminated water can contribute to atmospheric contamination. In the future, Smythe would like to add liquid contamination to the NAMS but it will be difficult because of the different ways that contaminated water can leave the site of an accident.

            Smythe focused on accidents involving civilian nuclear power stations and civilian and military fuel reprocessing plants. He disregarded nuclear explosions and accidents on nuclear powered ships and submarines.      Checked against 33 such quantified nuclear events during the past 60 years, a power law distribution is found. This means that most events are low in magnitude with a few events that are much greater. In the case of nuclear events, the highest magnitude events in descending order are Chernobyl, Three Mile Island, Fukushima and Kyshtym. It is estimated that there will be one such high magnitude event every twelve to fifteen years.

            The NAMS cannot predict the impact of an accident or the dosage that populations may be exposed to. But it can give an immediate accurate assessment of released radioactivity once an event has occurred. This is superior to the vague qualitative levels of the INES.

            On March 11, 2011 an earthquake and tsunami severely damaged four nuclear reactors at the Fukushima Number 1 power plant on the northeast coast of the Japanese island of Honshu.

            The Unit Four reactor is a boiling water design fueled with about eighty tons of uranium dioxide in zirconium alloy fuel rods. The primary concrete containment vessel surrounds the core of the reactor and the secondary concrete containment vessel included upper levels which contained pools for storing fuel rods and irradiated equipment.

            When the earthquake struck on March 11, the Unit 4 reactor was shut down. The fuel rods had been removed and placed in the pool on the upper level. On March 15 at 6 AM a hydrogen gas explosion at nearby Unit 3 blew two large holes in the walls the upper level of the Unit 4 building. Around 10 AM the spent fuel pool at Unit 4 caught fire releasing radioactive contamination. Employees were evacuated as the radiation in the Unit 4 building rose. The fire was extinguished by noon. Later, it was reported that there had been no sustained release of dangerous radioactive materials.

            At 4 PM on March 15 there was concern that the water in the pool might be boil and exposing the fuel rods. Visual inspections and analysis of the water in the pool at the end of April determined that the fuel rods were mostly undamaged. As of 10:30 PM the workers were unable to add water to the pool. TEPCO considered using helicopters to drop water into the Unit 4 building but it was postponed in favor of a plan to use high pressure fire hoses instead.

            Photographs from March 16 showed that a large part of the outer wall of the Unit 4 building had collapsed. There was an ongoing debate over whether the water in the Unit 4 spent fuel pond had boiled off completely. By 8 PM on the 16th, there was a plan to use a police water cannon to spray water into the pool. On March 18 it was discovered that the water in the spent fuel pool was vanishing faster than could be explained by evaporation which indicated that the water was leaking out. On March 20 military trucks were used to spray more water into the pool. For several days, seawater was poured into the pool with a concrete pump and also injected with the existing cooling system. Fresh water replaced seawater on March 29.

            Analysis of the water in the pool in mid-April indicated that a small number of fuel rods had been damaged and had released cesium-134 and 137 into the environment. Water continued to be pumped into the pool during April to control the rising temperature. There was a fear that too much water could structurally weaken the Unit 4 building. TEPCO decided that the disappearing water was being boiled off and not leaking out. TEPCO began constructing new columns in the Unit 4 building because of a fear that the building might collapse.

            In June it was found that there was only one third of the normal amount of water in the spent fuel pool and that some of the fuel rods were exposed. The fuel pool was refilled to the regular level to lower the radiation and temperature that prevented work on the pool. The new steel and concrete columns were completed by the end of June.

            Although the spent fuel pool at Fukushima Unit 4 is stable and under control at present, there is widespread concern over the vulnerability of the pool to future earthquakes. Japan is a very seismically active country and another major quake in the Fukushima area is likely. There is over eighty times the radioactive material in the Unit 4 pool than was released at Chernobyl which caused problems over much of Europe. Some say that the radiation that could be released from Unit 4 might threaten the very survival of the human race. Other are more conservative but do agree that the release of the fuel in Unit 4 into the environment would result in serious health and environmental consequences. A group of civic organizations has appealed to the United Nations to help clean up Unit 4. Authorities in the United States consider the Unit 4 pool to be a national security threat. Currently, the Unit 4 spent fuel pool is probably the number one environmental danger in the world.

            On March 11, 2011 an earthquake and tsunami severely damaged four nuclear reactors at the Fukushima Number 1 power plant on the northeast coast of the Japanese island of Honshu.

            The Unit Three reactor is a boiling water design fueled with both uranium dioxide zirconium alloy fuel rods and mixed uranium and plutonium oxide zirconium alloy fuel rods in zirconium alloy fuel rods. A solution of plutonium dioxide in water has a high boiling point and is not as prone to release into the environment during loss of coolant and steam venting. The primary concrete containment vessel surrounds the core of the reactor and the secondary concrete containment vessel included upper levels which contained pools for storing fuel rods and irradiated equipment.

            Around 3 PM Unit 3 was shut down in response to the earthquake. Around 5:30 PM all the electrical power generated by the reactor stopped with the arrival of the tsunami. Emergency batteries took over to provide power for monitoring and control systems and the coolant level was kep stable. When the water level began to drop again, the isolation cooling system and core sprayers were shut down and the high pressure coolant injection system was started. The injection systems failed on March 13th and could not be restarted. For a period of time, the top nine feed to the mixed uranium and plutonium oxide fuel rods were uncovered and radiation levels increased in the reactor building.

            Around 9 AM on March 13, steam was manually vented from the primary containment vessel and operators began using a fire truck to pump sea water mixed with boric acid into the reactor core but a malfunctioning gauge led to confusion about the actual level of water in the reactor. Around noon on March 13th, a government spokesman reported that hydrogen gas was building up in the Unit 3 primary containment vessel. At noon on March 14th the hydrogen gas was ignited and an explosion blew out the upper level walls of the Unit 3 reactor building. Eleven people were killed by the explosion and others were injured.

            There was concern that the Unit 3 fuel assembly could reach criticality and a self sustaining fission reaction would lead to massive releases of radioactive materials. Later analysis would show that criticality was never reached.

            On March 16th white plumes were seen rising from the Unit 3 reactor building. These plumes were assumed to be steam generated from water boiling off fuel rods stored in a pool at the top of the building. Helicopters were dispatched to dump cooling water on the top of the Unit 3 reactor but the mission was cancelled due to the high level of radioactivity. In August, the existing undamaged coolant injection system at Unit 3 was restarted. There were still problems with high temperatures in the upper levels of the containment building.

            Helicopters dropped loads of water on Unit 3 on March 17th. Fire engines sprayed sea water on Unit 3 for the next week to cool the reactor. On March 25th, fresh water replaced sea water in the spraying operation. There was a report on that date that the containment vessel at Unit 3 might have been breached and that radiation may have been released into the environment.

            It was estimated in April that thirty percent of the fuel rods had been damaged. In May it was reported that water sprayed into Unit 3 had been leaking back into the environment. In late June, it was revealed that chemical reactions in the injected water had become highly alkaline and was threatening to corrode the aluminum racks holding the fuel rods. This might have resulted in criticality, a self-sustaining fission reaction. By late September the cooling efforts successfully lowered the temperature in most of Unit 3 to under 100 degrees Celsius.

            On March 11, 2011 an earthquake and tsunami severely damaged four nuclear reactors at the Fukushima Number 1 power plant on the northeast coast of the Japanese island of Honshu.

            The Unit Two reactor is a boiling water design fueled with about eighty tons of uranium dioxide in zirconium alloy fuel rods. The primary concrete containment vessel surrounds the core of the reactor and the secondary concrete containment vessel included upper levels which contained pools for storing fuel rods and irradiated equipment.

            Around 3 PM Unit Two was shut down in response to the earthquake which shook the reactor and broke pipes. Around 5:30 PM all the electrical power generated by the reactor stopped. Emergency batteries were supposed to take over to provide power for monitoring and control systems but Unit 2’s backup batteries were damaged when the tsunami struck and could not provide emergency power. Fifteen minutes later, TEPCO, the company that managed Fukushima Number 1, declared a Nuclear Emergency Situation because they could not confirm that emergency cooling systems were injecting coolant into the core of Unit 2. Radioactive steam was released into the secondary containment vessel to reduce pressure in the primary vessel.

            At first, after the quake, TEPCO used the isolation condenser system to cool Unit 2 but after ten minutes, they shut down the isolation condenser and turned on the emergency cooling injection system which sprayed coolant into the reactor core. After a half hour, the loss of electrical power to the reactor disabled the spray cooling system but the operators were able to manually activate the cooling system. At 5 PM on March 12th, the cooling system shut down and restarted again at 9 AM on March 13th. Some building pressure was vented around midnight on March 12th. The operators worked problems with the fuel rod storage pool of Unit 2.

            Around noon on March 13th there was an explosion in the Unit 3 reactor building next to Unit 2. The explosion blew holes in the wall of Unit 2 and damaged four of the five cooling pumps in Unit 2.  The fifth pump shut down when its fuel was exhausted.  By 9 PM on March 14th, the cooling system was still operating and power had been restored from a mobile generator.

            The emergency cooling system was shut down by dropping pressure in the primary reactor vessel around 7:30 PM on March 14th. The fuel rods were exposed by dropping coolant levels and there were concerns about a possible core meltdown. The reactor was partly filled with water but rods were still exposed. The fuel rods were exposed because a monitoring gauge had been accidentally shut off preventing flow of coolant into the reactor. Seawater was pumped into the reactor on March 14th.

            There was an explosion in the Unit 2 reactor around 6 AM on March 15 but TEPCO and the Japanese government continued to report no significant breach of the reactor vessel though temperature and radiation levels were dangerously elevated. It was revealed by TEMPCO in May that the fuel rods in Unit 2 had melted down  around March 15th.

            By March 26th external electrical power had been restored to Unit 2.  Water was moved from the condensers in the reactor building to trenches and waste water treatment facilities. In May it was revealed that much of the cooling water injected into Unit 2 had leaked out of the containment vessel.

            Work continued through the summer of 2011 to reduce the temperature in Unit 2 with mixed results. In September of 2011was still too high at 114 degrees Celsius and more water was pumped into the reactor.

            In November, the detection of xenon-133 and 135 indicated that fission reactions were still occurring in the Unit 2 reactor. Huge amounts of boric acid were injected into the core to prevent the fissions reactions from achieving a self-sustaining criticality.

            In February of 2012, the temperature began fluctuating again. Temperature monitoring was hampered by damaged thermometers which could not be replaced due to high radiation in the reactor building of Unit 2. However, the temperatures did not exceed the 100 degree Celsius limit for considering a reactor to be in cold shutdown status.